These look like they could be useful - http://www.renderosity.com/mod/bcs/index.php?ViewProduct=77876
They look very nice on the page. I wonder if he/she has done other texture packs?
He has made other things. I don't know about textures. I bought a very nice tree from him once. You can click on his name to find all of his products.
He has some nice ground textures. I wonder if they have bump/displacement maps? I would probably use them in Blender. Terragen 2 does well itself.
http://www.renderosity.com/mod/bcs/index.php?ViewProduct=63317&vendor=Flink